1. Field of the Invention
The present invention relates generally to a broadcast communication system, and more particularly, to an apparatus and method for providing a frequency hopping scheme in a broadcast communication system.
2. Description of the Related Art
A broadcast communication system may use a frequency hopping scheme in order to prevent a deterioration in broadcast quality resulting from errors of a broadcast channel. For example, a broadcast communication system may provide a Time Frequency Slicing (TFS) scheme as illustrated in FIG. 1.
FIG. 1 illustrates a conventional frequency hopping pattern of a broadcast communication system.
Referring to FIG. 1, a broadcast communication system supports a first Radio Frequency (RF1) 100, a second Radio Frequency (RF2) 110, a third Radio Frequency (RF3) 120, and a fourth Radio Frequency (RF4) 130.
When a transmission end provides a broadcast service, the transmission end transmits a first broadcast signal 102 corresponding to the broadcast service via the RF1 100. After transmission of the first broadcast signal 102, the transmission end transmits a second broadcast signal 112 corresponding to the broadcast service via the RF2 110 according to a frequency hopping pattern. After the second broadcast signal 112 is transmitted, the transmission end determines an interval between a frame that transmits the first broadcast signal 102 and a frame that transmits the second broadcast signal 112 in consideration of an RF tuning time 104 of a reception end that receives the broadcast service.
When the reception end receives the broadcast service from the transmission end, the reception end receives the first broadcast signal 102 via the RF1 100. After the reception end receives the first broadcast signal 102, the reception end changes a frequency to the RF2 110 according to the frequency hopping pattern provided from the transmission end to receive the second broadcast signal 112 via the RF2 110.
As described above, the transmission end transmits a broadcast signal in consideration of the RF tuning time 104 of the reception end so that the reception end may receive a broadcast signal according to a TFS scheme. However, when a frame configured according to a Digital Video Broadcasting for a Second Generation Terrestrial (DVB-T2) system, a reception end may not receive a TFS frame due to a signal delay, such as illustrated in FIGS. 2A and 2B.
FIGS. 2A and 2B are diagrams illustrating a conventional construction for receiving a broadcast signal at a reception end of a broadcast communication system.
FIG. 2A illustrates a construction that cannot receive broadcast data due to a signal delay, and FIG. 2B illustrates a construction for receiving broadcast data with consideration of a signal delay.
As illustrated in FIG. 2A, when a frequency via which a reception end is to receive a broadcast service changes according to a frequency hopping pattern, the reception end performs RF tuning at an i-th frame 200.
After RF tuning is performed, the reception end changes a frequency and receives a broadcast signal via a first received (i+1)-th frame 210. For example, when using a DVB-T2 frame, the reception end obtains frame synchronization via a first preamble symbol P1 positioned at the start portion of a frame, and determines Fast Fourier Transform (FFT) size information of the system in signaling information of the P1 symbol. After determining the FFT size information, the reception end determines an FFT size for decoding a second preamble symbol P2 using the determined FFT size information, and obtains Guard Interval (GI) information via correlation or windowing of a received signal. After the GI information is obtained, the reception end may receive a GI and perform frequency fine tuning, etc. based on the P2 symbol and depending on the FFT size and GI information, and may then receive system configuration information (i.e., physical layer information) of the P2 symbol.
When broadcast data is received as described above, a delay may occur at the (i+1)-th frame 210 due to estimation of a GI of a P2 symbol and frequency fine tuning, so that the reception end may not decode a signal of an (i+2)-th frame.
Accordingly, as illustrated in FIG. 2B, the reception end changes a frequency, and then performs only an initial setting for receiving broadcast data via a first received (i+1)-th frame 210. For example, the reception end obtains synchronization during the (i+1)-th frame 210, determines an FFT size for decoding a P2 symbol, and obtains GI information. At this point, the reception end does not decode a P2 symbol of a broadcast signal and broadcast data received via the (i+1)-th frame 210.
After obtaining the GI information, the reception end decodes the P2 symbol and the broadcast data from an (i+2)-th frame 220 using the initial setting information determined via the (i+1)-th frame 210.
As described above, when changing a frequency of the reception end according to the frequency hopping pattern, the reception end cannot decode a P2 symbol of a first frame received via the changed frequency due to a signal delay and a processing delay. Accordingly, when a frequency changes, the reception end can receive broadcast data from a second frame.
When the broadcast communication system applies a TFS technique, the reception end cannot receive broadcast data transmitted via the first frame of the changed frequency.